1. Field of the Invention
The present invention relates to a mounting structure of electronic parts for mounting various electronic parts including acoustic parts such as speakers and others on a casing, and more particularly, relates to a mounting structure of electronic parts, which is suitable for mounting small information devices such as portable telephones.
2. Description of the Related Art
With developments in communication networks, use of information devices represented by portable telephones has been increasing. Most of the information devices employ acoustic parts for sound input and output to be used for making call and other various purposes. The typical examples of the acoustic parts are speakers and microphones. These acoustic parts are usually assembled in the interior of information devices. In such case, the casing of the information device is formed with at least an aperture for permitting sound to be transmitted between the assembled acoustic parts and the outside of the casing. The aperture permits not only the sound to pass therethrough but moisture, dust and other various foreign materials to enter the interior of the information device. These moisture and dust often become the cause for deteriorating the quality of the acoustic parts. Further, electronic parts operative to perform optical indications such as displays must suffer from such a problem that quality of the electric parts is degraded due to attachment of dust thereto. Thus, it is quite usual that a membrane-like member for protection from moisture and dust is disposed between the electronic parts such as acoustic parts that are accommodated in the interior of the information device and the aperture formed in the device casing.
FIG. 1 is a partial cross-sectional view illustrating an example of a mounting structure of electronic parts in a portable telephone, which is an example of the information device. Upper casing 11A and lower casing 11B which constitute the body of a portable telephone encloses inner cavity 12 of the body, in which printed circuit board 13 is disposed. On this printed circuit board 13 is mounted speaker body 14 as an acoustic part by the use of SMT, i.e., surface mount technology. Namely, terminals 15A and 15B made of a thin metallic sheet project from both side portions of speaker body 14 in the shape of an approximate cylinder. These terminals have one end curved in a L-shape, respectively, which is fixed to the surface of printed circuit board 13 by means of solder 16.
Upper casing 11A is bored with sound aperture 17 at a position opposing an upper middle of speaker body 14. Between speaker body 14 and upper casing 11A are mounted ring-like packing 18 made of urethane foam material and effectively discharging sound through sound aperture 17 without discharging it into the interior of the casing, and dust-proof net 19. Onto the upper surface of packing 18 is bonded first double-faced adhesive tape 21 in the shape of a ring identical with that of the packing in such a manner that the upper surface of the tape is bonded to upper casing 11A. Second double-faced adhesive tape 22 in the shape of a similar ring is attached to dust-proof net 19 of which the lower surface is bonded to the upper surface of speaker body 14.
Upon assembling these parts, an assembling operation is needed to attach dust-proof net 19 to the upper surface of speaker body 14 that is surface-mounted on printed circuit board 13, by the use of second double-faced adhesive tape 22. Another assembling operation is also needed to attach ring-like packing 18 to a portion around sound aperture 17 of upper casing 11A by the use of first double-faced adhesive tape 21. When these assembling operations are completed, ring-like packing 18 and dust-proof net 19 are fixed by pressure so that all parts are integrated into one piece.
According to the mounting structure of electronic parts, as shown in FIG. 1, the upper surface of speaker body 14 compresses packing 18 by constant pressure to come into tight contact therewith. Therefore, bonding of dust-proof net 19 to speaker body 14 as well as prevention of leakage of any sound can be realized.
Nevertheless, this prior art mounting structure of electronic parts needs to attach double-faced adhesive tapes 21 and 22 to separate parts, and accordingly requires two separate steps of assembling operations to be processed. Further, when packing 18 and dust-proof net 19, which are fixedly mounted in position by the use of double-faced adhesive tapes 21 and 22, respectively, are compressed to come into tight contact with each other, it is needed to adjust the positions of these two parts. This requires an additional works to do. Furthermore, the use of double-faced adhesive tapes 21 and 22 for bonding of the parts to one another needs that the bonded faces of respective parts must be kept clean during the bonding operation, and accordingly a problem that the parts must be adequately controlled during the assembling process occurs.
Therefore, the object of the present invention is to provide a mounting structure of electronic parts, which is capable of easily mounting electronic parts such as acoustic parts including a speaker and other various parts.
In a first aspect of the present invention, a mounting structure of electronic parts is formed by (i) a casing provided with an aperture through which sound wave is permitted to pass, and (ii) a cylindrical member arranged between the casing and an acoustic part for either input or output of the sound wave, which is fixedly disposed in the interior of the casing at a predetermined position opposing the aperture. The cylindrical member has one end thereof enclosing an end circumferential portion of an aperture opposed side of the acoustic part and is fitted to the end circumferential portion. The other end thereof is in press contact with a surface extending along an entire periphery of the aperture of the casing. The cylindrical member has a length extending from the aperture opposed end of the acoustic part to a casing side extreme end of the above-mentioned other end, being larger than a distance from the end of the acoustic part to a press contact position of the casing, when the above-mentioned one end is kept to be fitted on the acoustic part. And further, at least the other end of the cylindrical member is constituted by material having elasticity and deformed by pressure.
Accordingly when the acoustic part is accommodated in the casing, the other end of the cylindrical member comes in press contact with the periphery of the aperture of the casing. Thus, none of adhesive and double-faced adhesive tape is required.
In a second aspect of the invention, a mounting structure of electronic parts is formed by (i) a casing provided with an aperture through which sound wave is permitted to pass, and (ii) a member formed in a cylindrical shape as a whole and interposed between the casing and an acoustic part fixedly disposed in the interior of the casing at a predetermined position opposing the aperture for either input or output of the sound wave. The cylindrical member is kept in press contact with an entire periphery of the aperture by an opposing surface of the acoustic part, which opposes the aperture side, and a face extending along a periphery of the aperture of the casing. The cylindrical member has an axial length larger than a distance from the opposing surface of the acoustic part to a press-contact position of the casing, and at least portions of the cylindrical member in contact with the above-mentioned opposing surface and the casing being constituted by material that has elasticity and is deformed by pressure.
Thus, under a condition such that the acoustic part is accommodated in the casing, the other end of the cylindrical member comes in press contact with the periphery of the aperture, and therefore none of adhesive and double-faced adhesive tape is required.
Each of the present inventions as described above can further comprise a sheet-like member disposed so as to obstruct the interior of the cylindrical member to thereby prevent entrance of any moisture and dust.
The sheet-like member may be a net-like member having minute openings therein. The disposition of this sheet-like member can prevent moisture and dust from entering the acoustic part through the aperture.
In further aspect of the invention, the mounting structure of electronic parts is provided with a closing member deformed by pressure and blocking between the electronic parts disposed in the interior of the casing and the other parts in the interior of the casing.
Namely, the electronic parts disposed in the interior of the casing can be protected by the closing member that is deformed by pressure from the dust left in the interior of the casing.
The above objects, features and advantages of the present invention will become apparent from the following description based on the accompanying drawings, which illustrate an example of a preferred embodiment of the present invention.